The following is from data believed correct from Heritage and RR Auction websites. I can not vouch for accuracy or completeness:

Excluding unflown and medallions traded in 'sets', both Apollo 11 and 17 medallions traded at all-time high prices this year; Apollo 11 in May for $36,349, and Apollo 17 also in May for $61,976.

Of note, the average purchase price of six Apollo 11 trades in 2012-13 was $33,710 compared to $20,913 for nine trades in 2007-11. Apollo 17 had seven trades in 2012-13 at an average $50,407, compared to $31,603 for two trades in 2008-11. Both Apollo missions' medallions increased approximately 60% in the last two years from the average of 2007-11 trades.